Topological Defect Inflation

TL;DR

This paper investigates topological defect inflation, clarifies causal structures, extends models to Brans-Dicke gravity, and introduces a new domain wall inflation solution with relaxed coupling constraints.

Contribution

It provides new insights into the causal structure of inflating monopoles, extends defect inflation models to alternative gravity theories, and discovers a novel domain wall inflation solution.

Findings

Inflating monopoles are free from the graceful exit problem.

In Brans-Dicke gravity, inflating monopoles eventually stabilize.

A new domain wall inflation solution relaxes coupling constraints.

Abstract

We address some issues of topological defect inflation. (1) We clarify the causal structure of an inflating magnetic monopole. The spacetime diagram shows explicitly that this model is free from the ``graceful exit'' problem, while the monopole itself undergoes ``eternal inflation''. (2) We extend the study of inflating topological defects to Brans-Dicke gravity. Contrary to the case of Einstein gravity, any inflating monopole eventually shrinks and takes a stable configuration. (3) We reanalyze chaotic inflation with a non-minimally coupled massive scalar field. We find a new solution of domain wall inflation, which relaxes constraints on the coupling constant for successful inflation.